The invention relates to a device providing ultrasonic therapy to a female breast.
Major efforts have been made for the purpose of developing new noninvasive or minimally invasive methods of treatment of diseased, for example cancerous tissue. The advantage of such methods lies in a lower risk of complications during the treatment and in a more rapid healing process thereafter, since no open wounds need to heal. In this connection, the investigation and (further) development have also taken place of devices for ultrasonic thermotherapy in which diseased tissue is irradiated with focused high intensity ultrasound (high intensity focused ultrasound=HIFU) and the cancerous cells in the treatment area are destroyed by the resulting development of heat. With the HIFU method, it is possible, by reason of the focusing, to transport very high sound energies into a small target area having a diameter of, for example, a few millimeters. Within the focus region temperatures of 80xc2x0 C. and above may be reached, while in contrast there are no substantial temperature rises in the surrounding tissue and also in the regions which the ultrasonic waves traverse on their path to the focus region. As a result, it is possible to reach and treat diseased tissue in the interior of the body, without injuring healthy tissue. A prerequisite for the method is, however, a sound path into the target area, which sound path is free from bones and/or air inclusions, since these obstruct the propagation of sound and thus make effective focusing impossible. Initial investigations in the laboratory and also in the clinic have been carried out on the human brain, the eye, the prostate and also the female breast.
The reference titled xe2x80x9cRadiologyxe2x80x9d, March 1995, pages 731 to 737, contains a description of a configuration for the ultrasonic therapy of a female breast, in the case of which configuration a sonic transducer irradiates the breast of a female patient, who is lying on her stomach, in an upward direction (perpendicular to the plane of the body of the female patient). The sonic transducer is situated in a water-filled container, which is sealed off with an interface foil. The female patient lies directly on the interface foil. In the article, no statement is made concerning the ultrasonic coupling between the interface foil and the breast. By way of example, it is possible to use for this purpose a coupling gel which is described, in the case of a comparable application of ultrasonic therapy for the treatment of prostate complaints, in xe2x80x9cEur Urolxe2x80x9d, 1993, Vol. 23 (supplement 1), pages 29 to 33. For the monitoring of the temperature progression during the treatment, the female patient is situated together with the configuration for ultrasonic therapy in an MR installation.
In the publication xe2x80x9cEur Urolxe2x80x9d, 1993, Vol. 23 (supplement 1), pages 12 to 16, there is described in-vivo-treatments of muscle and tumor tissue with focused high intensity ultrasound. The temperature in the treatment area is likewise monitored by MR diagnosis. However, the subject of the investigations is in this case is not the female breast but tissue of living rabbits. In this case also, the animals are situated directly over the ultrasonic transducer, so that they are struck frontally by the soundwaves which are emitted upwards.
In the case of the devices for ultrasonic therapy which are known in the mentioned prior art, irradiation with ultrasound takes place in each instance frontally to the plane of the body. In this case, no consideration is given to the fact that it is also possible for bones to be situated behind the tissue to be treated. Since, in comparison with soft muscle tissue or adipose tissue, bones have an acoustic absorption that is approximately up to 40 times greater. When using this configuration there is the danger that the bones will be destroyed or at least damaged, in the case of unintentional inaccurate focusing of the ultrasound, by reason of the intense heating.
It is accordingly an object of the invention to provide a device for the ultrasonic therapy of a female breast with parallel sound direction which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which device, by suitable ultrasound guidance, eliminates the endangering of the bone system of the thorax, which bone system lies behind the breast, and at the same time provides good acoustic coupling.
With the foregoing and other objects in view there is provided, in accordance with the invention, a device for providing ultrasonic therapy to a breast of a female patient having a predetermined body plane, including: a container filled with at least one liquid for receiving a breast; and an ultrasonic transducer associated with the container, the ultrasonic transducer having a principal emission direction forming with a plane of a body of a female patient an angle of within minus 50xc2x0 and plus 50xc2x0.
In this case, the invention is based on the finding that, compared with the ultrasonic diagnosis which has been known for a great length of time in ultrasonic therapy, by reason of the focused high intensity ultrasound which is employed, new and additional aspects have to be taken into consideration. It was recognized above all that the very greatly differing acoustic absorption coefficients of different parts of the human body play a decisive role. By way of example, one and the same acoustic intensity may lead to virtually no temperature increase in soft tissue and to intense heating and permanent damage in the bones, which absorb 40 times better. Specifically in the case of the therapy of the female breast, particular importance has to be ascribed to this aspect, since adjoining the soft breast tissue together with the thorax there is a body region which has a particularly high proportion of bone.
In the case of the ultrasonic therapy of a female breast, the device according to the invention excludes in a simple manner the endangering of the thorax bones, in that the sound is not irradiated perpendicularly, but preferably parallel to the body plane or at most within an angular range of xc2x150xc2x0, related to the body plane, into the breast. By reason of the claimed advantageous angular range for the sound emission, even where the treatment area is close to the thorax, there is no increased danger of damage to the bone or periosteum due to inaccurate focusing. On the other hand, even with the lateral emission method according to the invention, it is in principle possible for all regions of the breast to be covered and thus treated. As a result of the introduction, according to the invention, of the breast into a liquid, e.g. into water, a better acoustic coupling than with gel is achieved. Coupling with gel always involves the danger of air inclusions, in particular in the case of coupling surfaces which are as large as the female breast, and of changes due to drying out where the periods of treatment are relatively lengthy. Consequently, the device according to the invention offers advantages with respect to the safety of the female patient (bone damage) and to the effectiveness (acoustic coupling).
Accordingly, in an advantageous refinement the breast is mechanically fixed, so that the region to be treated cannot change in its local position in the course of the period of treatment. In a further advantageous embodiment, for this purpose an acoustically transmitting fixing membrane is inserted between the breast and the ultrasonic transducer. If at least a part of the breast is advantageously pressed against this acoustically transmitting fixing membrane, then the result is the positioning which is fixed during the period of treatment. For improved adaptation to the anatomical nature of the breast, the fixing membrane can be defined in a plurality of parts, or in arched fashion and/or to be elastic. Preferably, the pressure is exerted against the fixing membrane by compression pads that are provided in the container. In this case, the compression pads may be disposed in such a way that they fix the breast to the fixing membrane not only in the direction of action but also in other spatial directions, in particular in the two spatial directions perpendicular thereto.
In the case of the device according to the invention, the ultrasonic transducer and the breast can advantageously be placed in separate partial regions of the container or in two separate containers. In order to achieve a good acoustic coupling, the partial regions or the two containers are filled with a first and a second liquid, preferably with water, in particular with degassed and deionized water. For reasons of hygiene, it is advantageous if the ultrasonic transducer and the breast are not situated in the same liquid. To this end, it is possible to provide, for example, a liquid-impermeable but acoustically transmitting separating wall between the ultrasonic transducer and the breast.
In a further advantageous embodiment, at least the temperature is recorded on that side of the breast that faces away from the ultrasonic transducer. In addition, or instead, a recording of the acoustic power is also possible there. Further embodiments provide further sensors, which may be fitted at any desired advantageous positions in the container. In the case of ultrasonic therapy, decisive importance is prescribed to the matter of what proportion of the acoustic power has been absorbed in the breast tissue to be treated. From the two recorded measured variables temperature and acoustic intensity, it is possible to draw conclusions as to the acoustic power absorbed in the breast and as to further quantities derived therefrom, such as, for example, the degree of destruction of the diseased tissue. The more sensors installed, the more accurately these statements can be made.
A mechanical adjustment system of the ultrasonic transducer is advantageously configured in two parts. The ultrasonic transducer can in the first instance be manually prepositioned and subsequently repositioned or finely positioned electrically, preferably by a hydraulic drive. The two-stage procedure permits a limitation of the expenditure that must be implemented for the hydraulic drive. Drives become all the more cost intensive the greater their region of adjustment. By the manual prepositioning, the ultrasonic transducer is already aligned in coarse terms onto the target area. In order to direct the focus precisely onto the diseased tissue, it is then only necessary for the hydraulic drive to carry out minor changes of position. Thus, the hydraulic drive manages with small ranges of adjustment, and can accordingly be configured economically. Also, the hydraulic drive can be configured for automatically positioning the ultrasonic transducer.
If the ultrasonic transducer is advantageously configured as a 2D (two-dimensional) array, the positioning of the focus of which may be electronically controlled in all three spatial directions, it is possible entirely to dispense with the electrohydraulic fine positioning. In this case, the mechanical adjustment system is accordingly only single-stage. It then includes merely the manual prepositioning. In an advantageous embodiment, the electronically controlled focus of the 2D array may be positioned in the entire breast region, without any need to undertake a mechanical change of position of the array. In this case, it is possible to dispense with a separate mechanical adjustment system.
As an advantageous variant refinement, the device according to the invention for ultrasonic therapy is used together with an MR diagnosis. With the aid of the data obtained from the MR-based temperature monitoring, the various setting variables of the device for ultrasonic therapy, such as for example sound direction and sound focusing, focus position and focus magnitude as well as the acoustic intensity, can be readjusted.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device for the ultrasonic therapy of a female breast with parallel sound direction, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.